Yulin18°13'N 109°31'E

According to some reports on base for the J11 [Su-27] is on Hainan Island at the Yulin
naval port, near Sanya City, the southernmost city of Hainan Province. This base is slightly more than 1,000 nautical miles away from Zengmu Atoll, the southernmost part of the Nansha [Spratly] Islands, barely within the Su-27's operational range.

The International Airport of Sanya City on the southern tip of Hainan Province, which was put into operation in 1994, is the only modern airport on the southern tip of Hainan Island. Sanya is one of the ten major tourist and holiday zones approved by the State Council, and local officials say that the opening of new international air routes in 1995 added to the development of the tourist business of Hainan.

It is also reported that a long range VLF transmitter is located on Hainan Island, probably near this naval air facility.

Hainan Island is also the location of a major signals intelligence facility.